Rudder counterbalance?

JBP-PA · Sep 7, 2023

From your profile, you are taking about the McGregor Venture 25? That has a kickup rudder? So the first thing is to make sure the rudder is all the way down. The second thing is to be sure your sail balance is correct, you really shouldn't have too much weather helm in normal conditions. Old sails can cause problems too.
That said, go for it. Attach a leading edge in front of the axis. Maybe 5-20% of the rudder area. Lots of boats have a balanced rudder or a partially balanced rudder. As you said, if you bolt it on, you can always take it off again.

rgranger · Sep 7, 2023

Does the boat want to round up into the wind? That is called weather helm. If your boat wants to point away from the wind, that is lee helm. Lee helm is dangerous! If that is what you have, you need to figure out why and fix it.

Most boats experience weather helm and that happens when the center of effort on your sails (combined) is behind the keel. It can be caused by blown out sails (need to buy new ones) or poorly trimmed sails (fixed by various means) or incorrect rake on the mast.

The Mac 25 is a swing keel... so you also have some play in where your center of lateral resistance sits on your boat. If you have weather helm, try raising the keel a few degrees? your keel will swing backwards and that will move the center of effort back a few inches. Don't get carried away with this approach but raising the keel a few inches can make a world of difference on the ballance of your rudder. It is usually a good idea to keep a little weather helm on the rudder. That way if something unexpected happens and you have to release the rudder, the boat will round into the wind and stall instead of other bad things happening.

I doubt you will find joy by simply bolting a piece of stock to the front of your rudder unless you can get the foil shape just right. The foil of the rudder produces lift when you tilt it and that helps the boat turn without dragging the rudder through the water more than necessary (breaking). So changing the rudder's foil can have some negative consequences.

rgranger · Sep 7, 2023

HeelBoy said:
I am working on a mechanical lock down (that isn't a through pin), but that's probably a winter project.

I have had good luck using nylon bolts (the type used to secure your toilet bowl to the floor). The bolt will shear if you hit something.

rgranger · Sep 7, 2023

BTW: I've never owned a Mac 25 but I've owned a Mac 2-22 and two Mac 21's. They have a similar keel and rudder design.

rgranger · Sep 7, 2023

HeelBoy said:
Background; I’m an engineer.

LoL

Yes... Engineer says... "if it ain't broken, it does not have enough systems"

Counter balancing your rudder will help but if your weather helm is from blown out sails, you are also heeling more and moving forward less... So it would be good to determine the source of your excessive weather helm. When I first got my H26, I could not keep her on her feet in anything above 12 kts. After new sails... JOY!

Let me ask a question. Is the weather helm always there or only after you heel over a bit? If it is the second, then the evidence is starting to lean towards blown out sails. Adjustments to the rudder won't help because when you heel a lot, much of the rudder comes out of the water anyway.

stickinthemud57 · Sep 7, 2023

Judging from your photo and video, it does not appear to me that your sails are blown out. I do see some issues with the mainsail, as outlined below.

Balancing your rig (sails and steering) are a good starting point. An airfoil rudder is a good step - when I replaced my stock rudder with one I did experience less weather helm and overall turbulence.

In my experience, excess weather helm is caused primarily by an overpowered mainsail. Experiment with mast bend (if your boat is equipped with an adjustable backstay, that is). Tightening the backstay flattens the mainsail, depowering it and reducing weather helm. This could help even in moderate breezes. It's possible that tightening the upper shrouds could accomplish this, but I would not see this as an ideal solution (to difficult to change in changing conditions.

In your video and photo it looks like the luff of the main is a little slack. This is the functional equivalent of tightening the cunningham, as it creates more curve in the sail near the intersection of the mast and boom, increasing power. Too much power at the main is a major cause of weather helm. When sailing in anything greater than light breeze, I would suggest you get that main halyard good and tight so there is no slack in the luff. This is not easy with your rig. Before I led my halyards aft (allowing me to use the winches to tighten the halyards), I used a snubbing winch on the mast to help with this, but these are not easy to find. Perhaps a clam cleat above the horn cleat on the mast will help hold tension while you get the halyard cleated off?

I find that fresh breeze means time to reef. I don't like to reef because wind speeds vary a lot on my little lake, but in your case it may be the thing to do. Flying too much sail will work against you, as your boat's hull speed will ultimately limit your potential speed. A properly balanced rig will give you better speed since it cuts down on turbulence at the rudder and windage from heeling.

As previously mentioned, keel angle will affect the balance of the boat, so once you have addressed your overall sail tuning, start experimenting with keel angle.

I use a quick-release clam cleat (Clamcleat CL257), mounted on my tiller. Holds the rudder down nicely, releases under stress, adjustable. I have not had to buy a new hold-down cable since I installed mine. Hard to find, but available on Ebay: Clamcleat ® CL257 Auto Release Cleat for Rudders 5024220125706 | eBay

The downside of decreasing weather helm in your case is that you might have to change your handle from "Heelboy" to "Sailing-at-25-degrees-tilt-or-less boy". Or not...

I have no experience with auto helms, so can offer no insights in that regard.

Best of luck, and happy sailing!

rgranger · Sep 7, 2023

You want the pocket to be about where I drew the green ovals in this image

And those sails look tired. But I see a few things that might help. Right now, your pocket is where I drew the red lines.. you want it where I drew the green lines...

First you need to get the luff flat. Add a down haul and pull the boom down just enough to get the crinkles out of the luff. The crinkles near the clew are also a sign of a poorly bent sail. I think your out haul is too tight. Try slackening the out haul until you see the pocket move forward a bit and play with the down haul and the out haul and try to get the crinkles out of your sail. You can also get stick on tell tails. These will really help you see the wind moving across your sail. They are cheap...

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It also looks to me like your jib sheet is too tight. You want to fatten up the head sail... keeping an eye on the pocket. And I can't see your head sails luff but make sure that is also crinkle free. Look at the sails in my avatar picture as an example. Also, your main does not have battens... I think you will find a lot more joy for the money if you start saving for a new main sail instead of investing in a rudder modification. The M25 was designed correctly when it left the factory so I doubt your troubles are from the rudder. It might just be the way the photo was taken but it also looks like your main sail's foot is too short for this boat.

stickinthemud57 · Sep 7, 2023

First of all, apologies for the multiple edits after initial posting. OCD, I guess...

You will like halyards led aft, especially if you can use a winch to tighten them. I HIGHLY recommend the Lewmar D1 double. Yes, an investment, but vastly superior to other designs. The "domino" design is easy on the ropes, and allows tightening even when fully locked down. Genius.

If you can get your mainsail luff tight using the halyard, that will obviate the need for a downhaul.

Variable winds. Ugh. Dumping wind is the only option sometimes.

I use a 4:1 block and tackle at my forestay, which works well for me.

Cheers!

rgranger · Sep 7, 2023

Do you have a proper traveler. @stickinthemud57 's suggestion to dump wind is made easier with a proper traveler. You can bring the main sheet block to windward then ease the sail out ... this will twist the top of the sail and dump wind up high (less heel) while keeping more of the main's driving force in the wind (speed through water). I added a make shift traveler to my H26 with parts off of ebay ($35). I could post more about that if you are interested.

rgranger · Sep 7, 2023

Here is what I did with my H26. I added the traveler at the bridge deck.

But if you want to conduct an experiment and see if swinging the sheet to windward and then letting the boom out helps.... you just need to take some line around the sheet and physically haul the sheet over... then let the boom out. Here is a pic of me doing this on my H26

This approach will not give you the full effect of a traveler but it is a good experiment to see if a traveler might give you the performance improvements you are looking for.

Joe · Sep 7, 2023

My suggestion is to quit speculating with different folks about this and that... the boat is OVER POWERED... simple as that. But... heh, heh, as you will soon realize, the essence of sailing to balance the boat's rig to achieve its most effecient performance in changing conditions/ You need to keep it simple. Get Don Gillette's Sail Trim guide, right here on SBO. You want to know what is happening, why and what to do to fix it. Good luck, have fun.

Rudder counterbalance?

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